Scott in the mix after WGC round one

Inspired by flashes of his brilliant best, Adam Scott is confident of firing on all cylinders in round two of the World Golf Championships-Bridgestone Invitational in Ohio.

The Australian world No.17 brushed aside four bogeys on the back nine after an electric start to ensure he finished the first round at Firestone Country Club just three shots off the pace, set by Belgian young gun Thomas Pieters on Thursday.

Scott, who won the WGC-Bridgestone in 2011, led the field for strokes gained in putting for a large part of day one but dropped two shots in his two closing holes to sign for a two-under-par 68.

"At times it felt really easy and at times it felt hard. It was scrappy at the end but there was really good stuff out there. It's a tough course and you can't play only 14 holes well at a WGC," Scott told AAP.

The 37-year-old Scott seemed to rediscover his world-class form with the driver, hitting nine of 14 fairways to be second in the elite WGC field for strokes gained off the tee.

"I'm certainly not searching for my game; it's there. The swing is looking good but I just have to manage my mistakes a little better these next three rounds. If I can do that, I'll be in for a really good tournament," he said.

Pieters, 25, set the pace with a 65 to climb to five-under and he will take a one-shot lead over Scotland's Russell Knox (66) into Friday's second round.

A six-way tie for third at three-under includes recently-crowned British Open winner Jordan Spieth, world No.4 Rory McIlroy and No.6 Jon Rahm, as well as two-timer Masters champion Bubba Watson, Kevin Kisner and Ross Fisher (all 67).

Scott shares ninth place with five others including world No.1 Dustin Johnson. He is the leading Australian with Scott Hend (70) next best at even-par in a tie for 22nd.

World No.7 Jason Day limped to a 71 to share 33rd, while fellow Australians Rod Pampling and Marc Leishman are tied for 53rd after the pair signed for 73.

Sam Brazel rounded out the Australian contingent with a 74 dropping him to 62nd.

The WGC-Bridgestone is a 76-man event with no 36-hole cut featuring the world's top 50 golfers and US PGA Tour winners from this season.